This weekend, I read the whitepaper on Rootstock, a Bitcoin sidechain. Heres the TLDR from a tweet thread I figured I'd post here too...
Rootstock (RSK) is a Bitcoin sidechain merge-mined with Bitcoin. About 40% of BTC hashpower participates in this, earning extra revenue to help secure BTC. Its native token, R-BTC, can only be created by locking up BTC in a 1:1 peg similar to Liquid's L-BTC peg.
There is no other issuance of R-BTC through a block subsidy, so miners only recieve tx (aka gas) fees. Although RSK's 2-way 1:1 SPV pegging mechanism resembles Liquid, Rootstock differs from Liquid by being a POW blockchain, rather than verified by a federation of blocksigners.
Besides Liquid's consensus mechanism, Liquid resembles Bitcoin more while Rootstock more resembles Ethereum, including it's account-based (instead of UTXO) model, resulting in it being highly compatable with Ethereum compilers, tools and dApps.
Several federated bridges exist between other smartcontract chains and RSK. RSK users can enjoy many of the features of Ethereum, (Defi, token/stablecoin issuance, NFT's, Turing-complete smartcontracts,) but without the uncertainty associated with issuance.
Since Ethereum's unpredictable issuance schedule is beyond control of its users, and in the hands of a priveleged few, RSK's native R-BTC being only created by pegging the world's most predictably issued currency is very welcome.
In addition, it's fair, pre-mine-free launch is in stark contrast to the Ethereum Foundation's hefty cut of coins it bestowed upon itself. And all gas fees that power R-BTC, and other Rootstock network assets, add well needed revenue to Bitcoin miners at no extra cost to them.
Although its features don't have much interest to me, I welcome more tools on Bitcoin's belt. I think it align's with Bitcoin's ethos. Fair, no pre-mine launch, no native token (Unlike Stack's STX!!,) and supports Bitcoin network security by providing extra revenue to miners.
Link to Rootstock website
https://www.rsk.co/